【作者】 董建聪；

【导师】 阎维平；

【作者基本信息】 华北电力大学 ， 热能工程， 2011， 硕士

【摘要】 近年来,我国火力发电机组逐渐向大容量、高参数方向发展。随着锅炉蒸汽参数的不断提高,过热器和再热器的结构设计也日趋复杂,这将不可避免地加剧管组内并联各管在热负荷与工质流量分配上的热偏差,由此引发的锅炉高温对流受热面超温爆管事故增多,严重影响了电站系统的安全、经济运行。因此,研究基于热偏差理论的锅炉高温对流受热面壁温计算模型以及建立壁温在线监测系统就具有非常重要的工程意义。针对电站锅炉高温对流受热面超温爆管现象,本文从蒸汽侧、烟气侧以及同屏各管的热偏差三个方面进行了理论分析;在总结前人研究成果的基础上,对现有壁温计算方法进行了一系列改进,提出了以管圈总吸热量为热力约束条件的具有可校核功能的分段计算模型,并对计算过程中所涉及到的局部热负荷、角系数和辐射因数等主要参数进行了理论推导和修正;还对高温对流受热面的爆管原因进行了分析,认为管壁金属长期高温蠕变是导致受热面失效的首要原因,选择并分析了能够适用于在线监测的受热面管壁金属高温蠕变寿命计算方法。以某电厂600MW亚临界锅炉为研究对象,对后屏过热器和末级再热器进行了管壁温度和金属高温蠕变寿命的实例计算,验证了上述理论及计算方法的准确性和可靠性。在此基础上,尝试开发了针对该台锅炉高温对流受热面的管壁温度在线监测系统。更多还原

【Abstract】 In recent years, the thermal power generation units have been developing in the trend of larger capacity and higher parameter. The structural design and arrangement of the superheater and reheater get complicated increasingly, which inevitably aggravate the hydrodynamic and thermal load deviation in the parallel tube set systems. It leads to the overheating and tube rupture on high-temperature convection heating surface of utility boiler, seriously decreasing the security and economy of the thermal power systems. Consequently, it is significant in engineering to study a computation model to calculate the tube wall temperature on high-temperature convection heating surface of utility boiler based on the thermal deviation and compile an on-line monitoring system.For the overheat and tube explosion on supetheater and reheater,this dissertation mainly analyzed theoretically the thermal deviation in three aspects that steam, gas and the heat deviation on the same panel tubes and made a series of improvements on the present computing model of tube wall temperature based on the previous research results. The verifiable subsection-calculating model which takes total heat-absorption in whole pipe loop as thermal restrictive condition was put forward. It also deduced and amended Angle Factor and Radiation Factor which will be used in the temperature calculation. Furthermore, the reasons of tube rupture were also discussed, and the long-term high temperature creep of tube metal was regarded as the primary cause of the heating surface failure. The paper analyzed and selected the high temperature creep remaining life calculation method which will be practicable under the on-line monitoring condition.In order to test the proposed theory and computing method, the applied calculation including tube wall temperature and creep remaining life were conducted on the hider-screen superheater and the high-temperature reheater of a 600MW subcritical boiler. Due to the above work,the on-line system applied in aforesaid boiler to monitor tube wall temperature on high-temperature convection heat transfer surface was exploited.更多还原